This invention relates generally to cooling chambers, and, more particularly, to a transmissive Dewar cooling chamber which is capable of mounting semiconductor crystal platelets therein for movement in two dimensions within a semiconductor ring laser
In recent years, the use of semiconductor devices has expanded greatly. An area of particular interest involving semiconductors is the optically pumped semiconductor laser. In fact, recent advances in laser research have led to the development by one of the inventors of optically pumped semiconductor lasers. Of particular interest are such lasers as described in an article by C. B. Roxlo, D. Bebelaar, and M. M. Salour, "Tunable CW bulk semiconductor platelet laser," Applied Physics Letters, Vol. 38, No. 7, April 1, 1981, pp 507-509 and an article by C. B. Roxlo and M. M. Salour, "Synchronously pumped mode-locked CdS platelet laser," Applied Physics Letters, Vol. 38, No. 10, May 15, 1981, pp 738-740.
In order to provide optimal outputs in such semiconductor lasers, the semiconductor platelets must be cooled to liquid nitrogen temperatures or below. This has been accomplished by one of the inventors by providing a uniquely designed Dewar cooling chamber for the above mentioned semiconductor platelet lasers. Such a Dewar cooling chamber is more fully described in an article by C. B. Roxlo and M. M. Salour, "Dewar design for optically pumped semicondcutor lasers," Review of Scientific Instruments, Vol. 53, No. 4, April 1982, pp 458-460 and is also described in U.S. patent application Ser. No. 361,020 filed on Mar. 23, 1982 and now U.S. Pat. No. 4,408,464 issued on Oct. 11, 1983.
With requirements for larger and larger output power much effort has gone into producing an optically pumped semiconductor laser having a ring resonant cavity. An example of such an optically pumped CW semiconductor ring laser can be found in U.S. patent application Ser. No. 552,554 filed together with this patent application by one of the inventors and incorporated herein by reference. The problems encountered in the past with respect to semiconductor lasers become even greater when dealing with the semiconductor ring laser. Because of bidirectional lasing associated with such semiconductor ring lasers, temperature control becomes even more critical. In addition, since tuning of such a laser is highly desirable it must also be possible to provide a temperature control within the cooling chamber. Unfortunately, the type of Dewar cooling system as described in the above-mentioned article in Review of Scientific Instruments and the above-identified U.S. Pat. No. 4,408,464 cannot be incorporated within the semiconductor ring laser. Therefore, without an appropriate cooling chamber for use within such a semiconductor ring laser it is virtually impossible for lasing to take place and for operation of such a laser to be reliable.
Consequently, it becomes essential to provide a mounting arrangement for the semiconductor crystal or crystal platelet within the semiconductor ring laser which not only allows for precise alignment of the crystal but also for accurate temperature control of the crystal, sufficient cooling of the crystal, and extremely tight pump beam focus upon the crystal to take place.